Tectonophysics Modeling of Baimka Ore Zone (Western Chukotka)

Abstract

Baimka ore zone (BOZ) containing the greatest in Russia Au-Cu-porphyry deposit “Peschanka” located in Alazey–Oloy fold belt and associated with Late Jurassic–Early Cretaceous volcanic belt complex. Ore zone originated in regional Aluchin fault, which controlled localization of intrusive bodies, Cu-porphyry systems, Au-Ag-polymetallic occurrences and placer gold deposits. Different-scaled paragenesis examinations led to interpret of these faults as right-hand shear, at the same time, to evidence a reverse movement by these shear zones with the left-hand shear preceding the right-hand shear movement. Ore localization controlled by deformation and several deformation phases results in heterogeneity of the environment that leads to complication of stress fields. The deformation process physical modeling in ore zone is an actual challenge, and experiments for shear zones with several intersecting sinuous faults and reverse movement have not been described so far. Tectonophysics modeling of Baimka ore zone performed at Moscow State University tectonophysics laboratory using modeling table with special modeling tool was constructed: a rectangular box made of four blocks that can be rotated over each other changing the form of the box from rectangle to parallelogram. Structural pattern of BOZ corresponds to two-phase reverse model of shear zones. Main faults were created in a left-hand shear and reactivated in right-hand shear conditions. Ore stock works and veins are concentrated in sites of local tension of right-hand shear. Modeling data can be used for the prognostication of ore zones. The main model fissures correspond to poorly studied potential ore fields allocated formerly in BOZ.